Product Description

Closed Circuit Cooling Towers principleThe cooling medium exchanges heat with the production process medium to obtain heat to cool the medium. The evaporation condenser transfers heat energy to the cooling tower spray water through heat exchange mode. After the temperature of the cooling medium drops, it is again transferred to the device for cyclic heat exchange. The spray water that receives the heat is recirculated through the latent heat of evaporation, and is recycled after cooling. See Figure 4.Figure 4 Principle of dry-wet combined Closed Circuit Cooling Towers Download original image1.6 Scope of the Closed Circuit Cooling TowersThe cross-flow form is mainly applied to the central air-conditioning system, and the downstream form is mainly applied to the hot and humid areas in the south, and the counter-current form is mainly applied to the arid regions in the northwest. The countercurrent dry-wet combined Closed Circuit Cooling Towers is suitable for use in high wind, drought, water shortage, sand, coal ash, high temperature areas, and the heat exchange medium is relatively less polluting. It is especially suitable for areas with harsh weather conditions and fragile ecological environment.2 Closed Circuit Cooling Towers process design2.1 Circulating water process input conditionsTotal circulating water volume:Media Name: Demineralized WaterInlet water temperature: 42 ° C (40 ° C)Effluent temperature: 32 ° C (30 ° C) 80 ° CDesign temperature: 80 ° CWorking pressure: 0.5MPadesign pressure:Design dry bulb temperature: 43.6 ° CDesign wet bulb temperature: 23.86 °CAltitude: 34.5mSummer average atmospheric pressure: 100.16k PaWinter average atmospheric pressure: 103.2k PaSummer relative humidity: 36%Winter relative humidity: 46%2.2 Dry and wet combined Closed Circuit Cooling Towers (40 ° C ~ 30 ° C) design parametersEquipment Name: Dry and wet combined with cooling towerSingle processing capacity: 530m3/hProcessing temperature:Total circulating water: 16000m3/hTotal number of equipment: 31 unitsDesign full air cooling condition temperature: 7 ° CHeat exchange tube material: 304 stainless steel (Cl-content in spray water should not exceed 300mg/L)2.3 Dry and wet combined Closed Circuit Cooling Towers (7 °C water stop) Comprehensive energy consumption calculation book2.3.1 Calculation of evaporation water consumption and power consumptionCirculating water temperature drop 42 ° C ~ 32 ° CThe total circulating water volume is 16000m3/hComplete water stop temperature point: 7 ° CChoose 27 dry and wet combined cooling towers54 fans in total, single power 55k WA total of 54 spray water inlets, a single port requires 12.5k W2.3.2 Calculating the amount of runawayAccording to the total spray water volume is 30,527,800 m3; the drift rate provided by the water collector manufacturer is 0.01% of the total spray water volume, and the total annual run-off amount is 0.3 million m3, see Table 1.Table 1 Temperature level and calculated power consumption data corresponding Download the original table2.3.3 Calculating the amount of blowdownDesigned according to 5 times concentration ratio, the total annual sewage discharge is 200,000 m3.2.3.4 Calculating total water consumption2.3.5 Calculation of power consumption of circulating water pumpRated flow rate: 3200m3/hRated head: 35mMotor power: 400k WMotor voltage: 10k VNumber of units: 5Annual power consumption = 5 × 400 × 8760 = 17.52 million k Wh

2.3.6 Calculation of total power consumption of closed system2.3.7 Summary of comprehensive energy consumption, see Table 2Table 2 Summary of closed comprehensive energy consumption Download original table2.4 Open system comprehensive energy consumption calculation2.4.1 Calculation of water consumptionAccording to the calculation method of GB50050-2007 "Design Code for Industrial Circulating Cooling Water Treatment", combined with the temperature table of this project:2.4.2 Calculation of power consumptionThe use of an open cooling tower requires the installation of a 185k W motor. The single treatment capacity is 4000m3/h, a total of 4 units are required. The annual power consumption of the fan is 5,942,200 kWh for 11 months.The circulating water system requires a 400k W water pump. The single circulating water volume is 2500m3/h, which requires a total of seven.Annual power consumption = 7 × 400 × 8760 = 24.528 million k WhTotal power consumption = 594.22 + 2452.8 = 307.02 million k Wh2.4.3 Summary of comprehensive energy consumption, see Table 3Table 3 Summary of open comprehensive energy consumption Download original table2.5 Closed system compared with open system2.5.1 Comparison of water saving rate calculationWater saving rate = (229.16-100.31) ÷229.16=56.2%2.5.2 Comparison of power consumption rate calculationPower consumption rate = (3047.02-4335.35) ÷3047.02=-42.3%

Design of the filter system next to the Closed Circuit Cooling TowersIn the design of the closed tower system, the method of centralized spray water is often used, that is, each closed tower does not have a spray water pump, leaving only the spray water inlet. The spray pool of the closed tower body only functions as a water collecting tank. The spray water of all closed towers is uniformly collected into a separate large circulating water pool, and then several large circulating water pumps are used to pump the water to each closed. The tower sprays into the water inlet. In this case, it is required to design a side filter system, and the side filter water generally takes about 5% of the total spray water.

The project adopts centralized water supply mode, which has no influence on the design and layout of the equipment body. However, the system design should consider three water stations, respectively designing circulating pool and shallow sand filter equipment. The single filter treatment water volume is 60m3/h.

3.2 Design of the Closed Circuit Cooling Towers dosing deviceIn order to prevent corrosion of heat exchange equipment and pipelines, slow down the scaling rate, prevent excessive growth of microorganisms, and ensure efficient and normal operation of the process heat exchange unit, it is necessary to add scale inhibitors and fungicides to the circulating water system. According to the existing spray water design, the medicaments are respectively added to the spray pool of each equipment, and the concentrated spray water can also be used to directly apply the medicament to the circulating pool.

3.3 Design of the expansion tower of the Closed Circuit Cooling Towers3.3.1 Setting the expansion pressure tankThe expansion pressure tank should have the functions of automatic nitrogen pressure regulation, water level detection, automatic water supply and drainage, and prevention of air entering the water system.

3.3.2 Closed Circuit Cooling Towers equipment requirementsThe volume ratio of gas to water should be 0.75~1. Including tanks, legs, closed manholes, and equipped with inflatable ports and inflation valves, water inlets and inlet valves, exhaust and exhaust valves, drains and drain valves, safety valves, pressure gauges, etc., and The interlock control system required for automatic voltage regulation. The pressure gauge signal and liquid level number of the expansion tank must be transmitted to the control room of the circulating water station.

4 Design points in high temperature, sand control, antifreeze, etc.4.1 Designed for high temperature protection(1) Two of the four fans are equipped with variable frequency fans, which can meet the design requirements when the temperature of the circulating cooling water is high and low.

(2) Use the patented nozzle spray water distribution facility to make the cloth uniform.

(3) Adopting high-efficiency energy-saving carbon fiber fan, the actual operating air volume is greater than the design air volume to ensure the summer cooling effect.

4.2 Designed in sand controlA sand blocking wall is installed at a certain distance from the cooling tower to prevent the sand from entering the circulating water system.

4.3 Designed in antifreeze and anticoagulation(1) Install a water tank on the outer column of the cooling tower to prevent ice from forming on the outer wall of the column.

(2) In addition, a water retaining plate is added at the four corners of the tower to prevent water from spilling outside the tower to form an ice hung.

(3) The upper tower pipe valve is separately provided with a bypass pipe to the cooling tower pool to prevent freezing of the circulating water in the winter pipe.

(4) On the upper edge of the cooling tower, arrange a return pipe to the bottom of the packing to prevent ice from freezing at the edge of the cold water tower.

4.4 Designed in terms of water saving(1) The cooling tower uses a high-efficiency water collector to reduce the loss of floating water, so that the loss of floating water is less than 0.001%.

(2) The air inlet adopts anti-vortex design to prevent water mist in the rain zone at the four corners of the air inlet. Because the vortex flows to the outside of the tower, the wind blows are completely cured.

Closed Circuit Cooling Towerss are based on the characteristics of local meteorological conditions and the fragile environmental requirements of the local ecological environment. The technical comparison of open cooling towers and Closed Circuit Cooling Towersng Towerss is carried out in the aspects of sand control, high temperature protection, antifreeze condensation, water saving and energy saving. Scientific and rational design, dry and wet combined with Closed Circuit Cooling Towers technology, Closed Circuit Cooling Towers application is a good feasibility.